Higher cortisol levels were associated with faster cognitive decline in older adults.
A study of nearly 3,900 older adults has found that higher cortisol levels and changes in the body’s daily stress hormone pattern were associated with faster cognitive decline. The research also found differences in cortisol levels between Black and white participants, although the connection between cortisol patterns and changes in thinking skills was similar across both groups.
The study included 3,895 adults with an average age of 76.7 years. Participants were part of the Chicago Health and Aging Project, a long-term research project that followed older adults living in four neighborhoods on Chicago’s South Side. Of the participants, 2,503 were Black and 1,392 were white. Researchers followed participants for as long as 11 years.
To examine cortisol patterns, researchers collected saliva samples at three different times during the day: morning, afternoon and evening. These measurements allowed the research team to examine overall cortisol levels and how the hormone changed throughout the day. The findings showed clear differences between Black and white participants. Black adults had lower overall cortisol levels and smaller changes in their hormone levels from morning to evening. Their cortisol patterns were also flatter throughout the day compared with those of white participants.
Despite these differences, the researchers found a similar relationship between cortisol patterns and cognitive decline in both groups. Participants who experienced greater changes in cortisol levels throughout the day tended to have slower cognitive decline. In contrast, those with the highest overall cortisol levels experienced faster declines in thinking skills.
Cortisol is part of the body’s natural response to stress. The hormone can cross the blood-brain barrier and attach to receptors in areas of the brain involved in memory, thinking and other mental skills. Researchers are interested in understanding whether long-term changes in cortisol may be connected to changes in brain health as people grow older.
The study also provides information about a population that has not always been well represented in research on aging. More than 60% of the participants were Black older adults, allowing researchers to examine cortisol patterns across racial groups using a large number of participants from both populations. Ng said the findings suggest that cortisol measurements could eventually help identify people who may face a greater risk of cognitive decline. However, further research is needed before saliva testing can be considered a useful way to assess an individual’s future brain health.
Researchers also found that cortisol patterns did not predict which participants developed Alzheimer’s disease during the follow-up period. This means the findings point to a relationship between cortisol and changes in cognitive ability, rather than showing that cortisol patterns can identify people who will develop the disease.
The results add to research examining how stress and the body’s response to it may relate to brain health in later life. Further studies could help determine whether cortisol measurements can provide useful information about cognitive aging and whether approaches to managing long-term stress could support older adults’ thinking skills.
Sources:
Salivary cortisol patterns predict cognitive decline in older adults
Salivary Cortisol and Cognitive Decline and Alzheimer Disease in Older Adults
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